The present invention relates to the industry concerned with the packing of substances in the form of a stick, such as lipsticks, crayons and other cosmetic products, as well as hemostatic sticks and other pharmaceutical products, or polishes and other maintenance products.
Such substances are usually placed in protective cases from which the stick is made to project at the moment of use by a sliding of a shifting lug or a rotation of a control knob. An opposite operation causes the stick to withdraw into a protected position inside the case until the next utilization.
In some cases employing a shifting lug, the stick is supported by a cup connected to a band which is made to slide in a groove of the case which curves in a direction perpendicular to the axis of sliding; this is in particular the case of the case described in French patent No 663-721. Such cases have the advantage of being operable in one hand, but customers mostly prefer cases with a rotary control notwithstanding the fact that they require the use of both hands.
In conventional cases having a rotary control knob, the stick is supported by a cup which slides inside two concentric sleeves, the inner sleeve being connected to rotate with the control knob and defining two diametrically opposed longitudinal openings, while the outer sleeve is relatively fixed and defines two diametrically opposed helical grooves. Two radial lugs extending from the cup each extend respectively through a longitudinal opening and into a helical groove.
Thus, by a rotation of the inner sleeve relative to the outer sleeve by means of the knob the cup rises or descends in the case, depending on the direction of rotation of the knob. Many patents disclose such cases and in particular the French patent No. 916 237. These rotary-knob cases are generally favoured by customers but they comprise elements which are rather delicate to manufacture and assemble, in particular owing to the fragility of the apertured sleeves. There is also known from the document US-A-2 250 876 a case for a stick of a non-fluid substance applicable by rubbing on a surface, comprising a tubular body in which is slidable a cup supporting the stick, and a control coaxial with the body and pivotable at one end of the case for sliding the cup and causing the stick to project through one open end of the body or, by means of an opposite rotation of the control, causing it to withdraw into the body; the cup in the body is connected to one end of at least one semi-flexible windable filiform member, i.e. a member which is laterally flexible but longitudinally rigid whose other end is connected to a winding drum which is coaxial with and connected to the pivotal control; formed in the inner surface of the tubular body is at least one longitudinal guide groove for each filiform element.
In this document, the control can only be rotated in a single direction for causing the stick to project from the case.